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Saturday, June 21, 2014

This years Salmoncon is approaching fast, it will be on July 12 and 13.

Last Year

Last year I put up a 40m Bottom Fed Delta Loop between two tall trees near my camp site. The results were Impressive. With a little effort, we worked all of the stations the we could hear on all HF bands with my FT-817 (at 5 watts).

(last years photo to be inserted here)

The top of the Delta Loop was at 90 feet AGL (some very tall trees) and was fed from the bottom with 450 ohm ladder line via a balun. We used the formula: "1005/Freq" to calculate the length of wire, which was folded in thirds to fine the corners.

In practice, the antenna resonated on a slightly higher frequency than I expected, but still within the 40m band. The LDG Z817 tuner on the FT-817 was able to match it on all HF bands. I may be wrong, but I think the impressive performance is due to the massive capture area of that much copper high in the air.

This Year

Because space and hight is available, I plan to double last years wire length, and put up an 80m Delta Loop. I am expecting good things, and will report the results.

There is a third tall tree that I might be able to use to convert the Vertical Delta Loop to Horizontal. It would be really fun to use an 80m Horizontal Loop at 90 feet AGL (I may need to splice in some more feed line).

Sunday, June 15, 2014

Currently, there has been several successful Alternate Minima Tuning Method installations on different users Builds. The Alternate Tuning Method is very smooth and intuitive, some of the additional (yet unassigned) buttons will be used for future menu functions.

Initially, there was a problem getting the Multiple Buttons to decode correctly on some microprocessor configurations. The problems consisted of slightly different internal analog pull-up resistors contained within the different microprocessor package styles, and a user error in wiring of one of the Minima Builds.

Once found, the simple wiring error was easily fixed.

But, the ATMEGA328P-PU and ATMEGA328-MU packages have slightly different internal pull-up values. Properly decoding seven switches on a single analog pin is very dependant on consistent pull-up resistor values, the way around the difference is to use an external pull-up (47K) and proper analog circuit wiring.

To help with button decode consistency, the analog support pins; AVCC, AREF, and AGND were properly configured to be used with pin 26. Pin 26 is connected to the FN Button in the original Minima circuit, and this pin is where the additional buttons resistor network are added.

The external pull-up is connected between AREF and pin 26, and AVCC is connected to +5V via a simple lowpass filter (see diagram).

The Alternate Minima Tuning Sketch which support Multiple Push Buttons is available at the GitHub. Currently it is "alpha" code, but I will update the URL when it has been "committed" to production.

Saturday, June 14, 2014

To properly and simultaneously support different ATMEGA328P packages (e.g., -PU and -MU) for use in the Minima, I suggest the FN push button circuit to be augmented to correctly use the analog AVCC, AREF and AGND pins.

Hopefully this will allow a single Revision of the Sketch to support all ATMEGA328P microprocessor packages.

Note: this circuit and sketch are "alpha" and should only be use to help test this solution.

Friday, June 13, 2014

My proposed Minima Transceiver button enabling software will assume the addition of six buttons (7 total) connected in parallel with the original FN button (btn1). The software will continue to evolve to include new functions based on these buttons.

The first two buttons (btn2-3) will be used to move the "Cursor" for tuning.

The rest of the buttons (btn4-7) will have definitions based on planned software additions which will include interactive menus, where "Up - Down" and "Left - Right" will have some implied meaning. The suggested "diamond" layout of buttons 4-7 is similar to consumer products with key pads.

I suggest button groups something like the following:

Proposed Button Layout

Of course, the actual layout is up subjective and up to you.

Actual button "labels" will be suggested as the software evolves.

I would also suggest you stay flexible, and plan your Front Panel Layout with replacement and changes in mind.

Also, I welcome other ideas for button use, layouts and menu strategies.

Tuesday, June 10, 2014

John suggested that moving the cursor via (additional) buttons would work much better than waiting for the cursor mode to automatically switch intervals as I proposed.

The problem is the original Farhan's Minima does not have extra pins available for dedicated connections for additional switches. John suggested maybe we abandon pins 2 and 3, because he has an alternate method of programming his Arduino. I checked the possibilities and it could be done at the expense of Arduino Bootloader use, and at the expense of the programmer DEBUG output. Nether of which I would like to abandon.

But

An alternate method was suggested by someone (?) on the Minima Reflector, more User Buttons can be provided by a network of Resistors and Switches on an analog pin.

The current FN Switch is on an analog pin, and switches (and resistors) can be added in parallel.Currently

I have successfully added six additional Switches in parallel to the original FN switch, and have written a Sketch Modification to decode them.

I was able to retain the original FN button's definition; Momentary, Double Push, and Long Push.

The first two new switches will be used to move the cursor; "Left" and "Right".

Current the other four switches are currently being defined as the Sketch is being changed.

This new (and preliminary) User Interface (UI) works very natural and smoothly with my new Sketch. I will soon publish the NEW Sketch that I used to decode these switches (unfortunately, I currently have another major project that is interfering with this Hobby project).

Wednesday, June 4, 2014

The last few days I have be struggling with my least favorite Homebrew build type of circuits, and that is the Audio Modules for the Minima Transceiver. I general, I just do not like to build Audio circuits.

Originally when I started the Minima Build, I was planning to build each schematic section as separate modules. For the RF sections that approach has work well. My original attempt to build modules for the Audio sections failed because they are somewhat dependent on each other, and therefore many interconnecting pins were going to be necessary to connect everything together. My original thought was to arrange the five Audio modules into a "checker board" with edge header between each. The first layout with headers on several sides of the modules eliminated their general use as building blocks for other projects. I wanted an easily adaptable modules for future projects. Because the module approach became to complex and therefore after several days (weeks) I abandoned the Module approach for the Audio Circuit - FAIL.

I collected the modules together into a single complex layout, but thats is where it sat for several weeks, although I publish blog posts with photos, diagrams, and discussions about the project. I was still not happy with the design or the approach.

But I needed to get something done to show progress on my Minima Build. Three days ago, I decided to Build the Audio Board with the Toner Transfer Method (the same as with all of my modules). The Audio Board was going to be about 2.5x5.0 inches with 84 hand soldered via's. I printed, etched, dilled, and solder wiped the board and got it ready to install the 84 via's. But each time I looked at hand soldering 84 via's the number looked like a bigger task, and my interest diminished. I again abandoned the complex Audio Board, as there has got to be a better way!! - Another FAIL.

An Idea

The solution may be going back to individual modules, but this time I am going to stand-up each module on its edge Header. There will be five modules as described on the original schematic, and one power supply module. The modules will stand on a group of spaced headers on a Audio Mother board. These modules will easily work with ProtoBoards for experiments and testing, and therefore satisfying my original goal for the Minima.

I have now completed the layout for each Module and the Mother Board. The Mother Board is about 1.5x5.0 inches. Each of the five modules will be 1.0x1.0 inches square. The Relay Module is a little larger.

The Mother Board will contain the Module Headers, Jacks, the edge connector headers for the Digital Controller Board, Tuning Pot, and Volume Control. It will be the "Glue" that connects all of the Modules together.

Mother Board, Five Modules anda Power Supply Module

These boards will be created using the Toner Transfer Method.

With this new approach, I have a design (with only a few via's) that will hold my interest, and therefore my Minima Project Build should now continue forward. I can build a Module when I have time with very little overhead.

If this prototype works, I may send the design out for professional manufacture.

Sunday, June 1, 2014

This post is for a few brave (adventuresome) Minima builders/users. This
is a "work in progress" and therefore feedback is requested.

Although I have not completed my experimental Minima Transceiver build, I have built the Digital Control Module and have been working on the Arduino software that controls the Display and the rest of the Minima hardware. See my previous blog posts, or at:

One of the modification that I have made is to incorporate Jeff's (KO7M)1Hz Driver for the Si570. This modification allows for 1Hz Tuning of the my Minima's VFO. Jeff's Si570 code is available on GIT Hub at:

Also, I have been working to modify the Arduino Sketch to provide an Alternate Tuning Method, what I consider a "Near-Normal" tuning method or functionality, for the original Farhan's Minima circuit and hardware. With only the original circuit's tuning POT to work with, functionality is of course somewhat limited.

The original Minima Arduino Sketch (REV 0.4) changes frequency via the Tuning Pot and pre-programmed steps. Tuning rate is dependent on how far from the "center of rotation" the Tuning Pot is turned. To tune "up and down" around a received signal the Tuning Pot must be turned past the Pot's center location, which of course is not typical of a normal receiver. Farhan's original Minima Arduino Sketch (REV 0.4) is available at:

The original Minima Arduino Sketch of VERY functional. But, I as programmer, and like they say: "programmers will be programmers, and they will modify programs", so, I am, what I am :-)

My goal for this program modification is to maintain the functionality of the original Minima Arduino Sketch and incorporated Jeff's Integer Si570 Driver, which provides High Resolution Tuning (< 1Hz).

My modified Sketch, can replace the original Minima Sketch (REV 0.4) via a normal Arduino IDE compile and download. And if needed, the original Sketch can be re-installed via the same method.

This modified Minima Sketch (REV 0.4.erb) is available on my GIT Hub, at: